The manufacture of semiconductor wafers to create semiconductor integrated circuit devices typically involves a sequence of processing steps which fabricate the multi-layer structure generally associated with the integrated circuit devices. Such processing steps may include (1) the deposition of metals, dielectrics, and semiconductor films, (2) the creation of masks by lithography techniques, (3) the doping of semiconductor layers by diffusion or implantation, (4) the polishing of outer layers (e.g. chemical-mechanical polishing), and (5) the etching of layers for selective or blanket material removal.
It should be appreciated that it is generally necessary to maintain relatively precise control of the temperature of a semiconductor wafer during performance of certain of the processing steps associated with manufacture of the wafer. For example, a number of processing steps associated with wafer fabrication involve complex chemical reactions which require the temperature of the semiconductor wafer to be controlled within predetermined specifications.
To this end, a number of concepts have heretofore been developed to measure the temperature of a semiconductor wafer during wafer fabrication.
For example, temperature sensors are utilized within a chamber or the like in which the semiconductor wafer is located in order to measure the temperature of the air or other gas within the chamber. The temperature of the semiconductor wafer is then estimated or otherwise derived from the temperature of the air or other gas within the chamber. Moreover, thermocouples have heretofore been secured to a chuck or other type of wafer handling device in order to measure the temperature of the handling device. The temperature of the semiconductor wafer is then estimated or otherwise derived from the temperature of the handling device.
However, such heretofore designed concepts have a number of drawbacks associated therewith. For example, both aforementioned concepts (i.e. use of the temperature sensors within a chamber or thermocouples on a handling device) determine the temperature of the semiconductor wafer indirectly. In particular, both aforementioned concepts require that the temperature of the semiconductor wafer be estimated or otherwise derived from a temperature measurement that is not taken directly from the wafer.
In an attempt to overcome the drawbacks of indirect temperature measurement, a number of concepts have heretofore been developed in an attempt to directly measure the temperature of a semiconductor wafer. For example, optical pyrometers have heretofore been utilized in an attempt to directly measure the temperature of a semiconductor wafer during wafer fabrication. However, use of optical pyrometers has typically not produced consistent measurements due to variations in wafer emissivity.
What is needed therefore is a method and apparatus for determining the temperature of a semiconductor wafer during fabrication thereof which overcomes one or more of the aforementioned drawbacks. What is particularly needed is a method and apparatus for measuring temperature of a semiconductor wafer which measures the temperature of the wafer directly. What is further needed is a method and apparatus for measuring temperature of a semiconductor wafer which measures the temperature of the wafer in-situ.